The i915 Gallium3D driver isn't officially maintained by Intel, only the i915 classic Mesa DRI driver as with the i965 classic DRI driver too. However, Google and other stakeholders over the years have invested quite a bit into "i915g" and brought it into good support though the performance isn't always better.
Last year a Google Chromium developer brought sRGB textures / OpenGL 2.1 support to i915 Gallium3D. Now with talk of possibly changing the old Intel hardware default from i915c to i915g, Intel's Eric Anholt has made some improvements to their official classic driver.
Eric's first i915 driver change on Monday was always enabling OpenGL 2.0 support rather than OpenGL 1.4 as the case has been. Immediately following that was another commit to add support for GL_EXT_texture_sRGB and GL_EXT_texture_sRGB_decode.
This is just like the Intel Gallium3D work from last year and with the sRGB extensions there is now OpenGL 2.1 compliance for Intel's classic i915 driver.
We'll see in due time if the i915 Gallium3D driver ends up becoming the default or the i915 classic driver is to still be maintained here and there by Intel's Open-Source Technology Center.